U.S. patent application number 14/463033 was filed with the patent office on 2015-09-24 for brilliant toner, electrostatic charge image developer, toner cartridge, and process cartridge.
The applicant listed for this patent is FUJI XEROX CO., LTD.. Invention is credited to Akihiro IIZUKA, Motoko SAKAI, Mona TASAKI.
Application Number | 20150268570 14/463033 |
Document ID | / |
Family ID | 54142002 |
Filed Date | 2015-09-24 |
United States Patent
Application |
20150268570 |
Kind Code |
A1 |
SAKAI; Motoko ; et
al. |
September 24, 2015 |
BRILLIANT TONER, ELECTROSTATIC CHARGE IMAGE DEVELOPER, TONER
CARTRIDGE, AND PROCESS CARTRIDGE
Abstract
A brilliant toner includes flake shape toner particles
containing a binder resin and a flake shape metallic pigment. The
brilliant toner further includes tabular particles containing a Ti
element.
Inventors: |
SAKAI; Motoko; (Kanagawa,
JP) ; IIZUKA; Akihiro; (Kanagawa, JP) ;
TASAKI; Mona; (Kanagawa, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJI XEROX CO., LTD. |
Tokyo |
|
JP |
|
|
Family ID: |
54142002 |
Appl. No.: |
14/463033 |
Filed: |
August 19, 2014 |
Current U.S.
Class: |
430/105 ;
430/108.3 |
Current CPC
Class: |
G03G 9/0827 20130101;
G03G 9/0902 20130101; G03G 9/09708 20130101; G03G 9/08 20130101;
G03G 9/0821 20130101; G03G 9/0819 20130101 |
International
Class: |
G03G 9/00 20060101
G03G009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 20, 2014 |
JP |
2014-058854 |
Claims
1. A brilliant toner comprising: flake shape toner particles
containing a binder resin, and a flake shape metallic pigment; and
tabular particles containing a Ti element.
2. The brilliant toner according to claim 1, wherein a moisture
content of the tabular particles is from 1% by weight to 10% by
weight.
3. The brilliant toner according to claim 1, wherein a value of
height/long axis of the tabular particles is from 0.1 to 0.7.
4. The brilliant toner according to claim 1, wherein a number
average particle size of the tabular particles is from 7 nm to 50
nm.
5. The brilliant toner according to claim 1, wherein a ratio (C/D)
of an average maximum thickness C and an average equivalent circle
diameter D of the toner particles is from 0.001 to 0.500.
6. The brilliant toner according to claim 1, wherein a ratio (C/D)
of an average maximum thickness C and an average equivalent circle
diameter D of the toner particles is from 0.001 to 0.200.
7. The brilliant toner according to claim 1, wherein a value of
height/long axis of the tabular particles is greater than a value
of a ratio (C/D) of an average maximum thickness C and an average
equivalent circle diameter D of the toner particles.
8. The brilliant toner according to claim 1, wherein a value of
height/long axis of the tabular particles is 1.1 times to 25 times
the value of a ratio (C/D) of an average maximum thickness C and an
average equivalent circle diameter D of the toner particles.
9. An electrostatic charge image developer comprising the brilliant
toner according to claim 1.
10. A toner cartridge that accommodates the brilliant toner
according to claim 1, and is detachable from an image forming
apparatus.
11. A process cartridge comprising: a developing unit that
accommodates the electrostatic charge image developer according to
claim 9 and develops an electrostatic charge image formed on a
surface of an image holding member with the electrostatic charge
image developer as a toner image, in which the process cartridge is
detachable from an image forming apparatus.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims priority under 35
USC 119 from Japanese Patent Application No. 2014-058854 filed Mar.
20, 2014.
BACKGROUND
Technical Field
[0002] The present invention relates to brilliant toner, an
electrostatic charge image developer, a toner cartridge, and a
process cartridge.
SUMMARY
[0003] According to an aspect of the invention, there is provided a
brilliant toner including:
[0004] flake shape toner particles containing a binder resin, and a
flake shape metallic pigment; and
[0005] tabular particles containing a Ti element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Exemplary embodiments of the present invention will be
described in detail based on the following figures, wherein:
[0007] FIGS. 1A and 1B are schematic views showing toner particles
which lie due to a physical force of a fixing member, in which FIG.
1A shows a case of using toner including toner particles which are
easily aggregated and FIG. 1B shows a case of using toner including
toner particles which are hardly aggregated;
[0008] FIG. 2 is a cross-sectional view schematically showing an
example of toner particles of an exemplary embodiment;
[0009] FIG. 3 is a schematic configuration diagram showing an
example of a fixing device of an image forming apparatus of the
exemplary embodiment;
[0010] FIG. 4 is a schematic configuration diagram showing an
example of an image forming apparatus of the exemplary
embodiment;
[0011] FIG. 5 is a schematic configuration diagram showing an
example of a process cartridge of the exemplary embodiment; and
[0012] FIG. 6 is a schematic view for illustrating a contact
angle.
DETAILED DESCRIPTION
[0013] Hereinafter, exemplary embodiments of a brilliant toner, an
electrostatic charge image developer, a toner cartridge, a process
cartridge, an image forming apparatus, and an image forming method
of the invention will be described in detail.
[0014] Brilliant Toner
[0015] The brilliant toner of the exemplary embodiment
(hereinafter, referred to as "toner" in some cases) includes: flake
shape toner particles containing a binder resin and a flake shape
metallic pigment; and particles containing a Ti element
(hereinafter, referred to as a "Ti-containing particles" in some
cases).
[0016] Since the brilliant toner of the exemplary embodiment has
the configuration described above, an image having a high
brilliance is obtained even after deterioration of the toner,
compared to the toner not including the Ti-containing particles
(for example, toner formed of toner particles or toner using
particles containing an Si element instead of the Ti-containing
particles). The reason thereof is not clear but may be assumed as
follows.
[0017] It is found that, as in the exemplary embodiment, in a case
of performing image forming using the toner including flake shape
toner particles and containing a metallic pigment, in a step of
transferring a toner image onto a recording medium, the transferred
toner particles are in an upright state (that is, a state in which
a long axis direction of the toner particles is closer to a
direction orthogonal to a surface of the recording medium than a
direction parallel with the surface of the recording medium) due to
a transfer electric field. The toner particles in the upright state
lie due to a physical force of a fixing member which contacts a
toner image in a fixing step of fixing the toner image onto the
recording medium.
[0018] The "long axis direction" herein means a direction of the
longest axis.
[0019] The brilliance of the fixed image is dependent on
orientation and arrangement of the toner particles in the fixed
image. In detail, as the toner particles are oriented in a state
where the long axis direction thereof is close to the direction
parallel with the surface of the recording medium and the toner
particles are densely disposed in an image portion, a high
brilliance is obtained. The orientation and arrangement of the
toner particles in the fixed image are dependent on easiness of
aggregation of the toner particles.
[0020] FIGS. 1A and 1B schematically show the toner particles in
the upright state on the surface of the recording medium which lie
due to the physical force of the fixing member, in a case of using
toner including toner particles which are easily aggregated (FIG.
1A) and a case of using toner including toner particles which are
hardly aggregated (FIG. 1B).
[0021] As shown in FIG. 1A, in a case where the toner particles are
easily aggregated, toner particles 2 transferred onto a surface of
a recording medium 6 are aggregated in the upright state, and
accordingly the toner particles 2 are unlikely to lie even when the
physical force is applied by a fixing member 8, and the toner
particles are easily overlapped with each other. Therefore, even
after the fixing step, it is difficult to set the long axis
direction of the toner particles 2 to follow the direction parallel
with the surface of the recording medium 6, and the toner particles
2 are easily disposed in a biased manner.
[0022] Meanwhile, as shown in FIG. 1B, in a case where the toner
particles are hardly aggregated, the toner particles 2 transferred
onto the surface of the recording medium are arranged at intervals,
and accordingly, the toner particles 2 easily lie due to the
physical force of the fixing member 8 and are easily arranged not
to be overlapped with each other. Therefore, the toner particles 2
are easily oriented in a state where the long axis direction
thereof is close to the direction parallel with the surface of the
recording medium 6, and the toner particles 2 are easily evenly
disposed in the image portion.
[0023] In the toner, the toner particles are easily aggregated in
general, along with the proceeding of deterioration. In detail, for
example, in some cases, an external additive is embedded in the
toner particles due to a physical load applied to the toner by
stirring or the like in a developer unit, and the action of the
external additive of physically reducing an adhesive force between
the toner particles is not obtained, and therefore the toner
particles may be easily aggregated. Particularly, in a case where
the toner particles have a flake shape, a contact area of toner
particles is large, and accordingly the aggregation due to the
deterioration of the toner is significant.
[0024] With respect thereto, since the Ti-containing particles are
used as the external additive in the exemplary embodiment, the
Ti-containing particles allows the charge stored in the toner
particles to leak, an electrostatic adhesive force between the
toner particles is reduced, and accordingly the toner particles are
hardly aggregated. The reduction of the electrostatic adhesive
force performed by the Ti-containing particles is not a physical
action but an electrical action, and therefore it is exhibited even
when the Ti-containing particles used as the external additive are
embedded in the toner particles. In addition, the Ti-containing
particles are hardly separated from the toner particles when the
Ti-containing particles are embedded in the toner particles, and
accordingly it is easy to obtain the effect of the reduction of the
electrostatic adhesive force.
[0025] As described above, in the exemplary embodiment, it is
expected that the aggregation of toner particles hardly occurs even
after the deterioration of the toner and accordingly an image
having a high brilliance is obtained, compared to a case of not
using the Ti-containing particles.
[0026] When an average of an equivalent circle diameter
(hereinafter, referred to as an "average equivalent circle
diameter" in some cases) of a surface with a maximum projection
area of the toner particles (hereinafter, referred to as a "flake
surface" in some cases) is set as D (.mu.m) and an average of
maximum values of a thickness orthogonal to the flake surface
(hereinafter, referred to as an "average maximum thickness" in some
cases) is set as C (.mu.m), the phrase "the toner particles have a
flake shape" in the exemplary embodiment means that a value of C is
smaller than a value of D.
[0027] Herein, the average maximum thickness C and the average
equivalent circle diameter D of the toner particles are measured
with the following method.
[0028] The toner is applied to a flat surface and dispersed with
vibration so as not to have unevenness. 1000 toner particles are
observed with a color laser microscope "VK-9700" (manufactured by
Keyence Corporation) with a magnification power of 1000, the
maximum thickness C and the equivalent circle diameter D of a top
view are measured, and arithmetic average values thereof are
calculated to acquire the average maximum thickness C and the
average equivalent circle diameter D.
[0029] In the same manner as in the case of the toner particles,
the phrase "the metallic pigment has a flake shape" in the
exemplary embodiment means that the average maximum thickness C is
smaller than the average equivalent circle diameter D.
[0030] The observation of the average maximum thickness C and the
average equivalent circle diameter D of the metallic pigment is
also performed in the same manner as in the case of the toner
particles, the maximum thickness C and the equivalent circle
diameter D of a top view of the brilliant pigment contained in the
toner particles are measured, and arithmetic average values thereof
are calculated to acquire the average maximum thickness C and the
average equivalent circle diameter D.
[0031] The "brilliance" in the exemplary embodiment means that
brilliance such as metallic gloss is obtained when the formed image
is visually observed.
[0032] As an image having a brilliance, an image which has a ratio
(A/B) of a reflectance A at a light receiving angle of +30.degree.
and a reflectance B at a light receiving angle of -30.degree.,
measured with the image which is irradiated with incident light at
an angle of incidence of -45.degree. by a goniophotometer, is from
2 to 100
[0033] The value of the ratio (A/B) which is equal to or more than
2 represents that the reflection at the side opposite the incident
light (side of the positive light receiving angle) is greater than
the reflection at the side of the incident light (side of the
negative light receiving angle) and diffuse reflection of the
incident light is suppressed. Ina case where the diffuse reflection
that incident light is reflected to various directions occurs, the
color appears to be darkened when visually observing the reflected
light thereof. Accordingly, when the ratio (A/B) is equal to or
more than 2, the gloss is confirmed and the excellent brilliance is
obtained when visually observing the reflected light thereof.
[0034] Meanwhile, if the ratio (A/B) is equal to or less than 100,
a viewing angle with which the reflected light can visually
observed is not excessively narrow, and accordingly, a phenomenon
in which the color appears to be black depending on an angle is
unlikely to occur.
[0035] The ratio (A/B) described above is more preferably from 20
to 90 and particularly preferably from 40 to 80.
[0036] In addition, as described above, in the exemplary
embodiment, an image having a high brilliance is obtained even
after deterioration of the toner. The ratio (A/B) of the image
formed after the deterioration of the toner is preferably 2 to 100
and particularly preferably 40 to 80.
[0037] Measurement of Ratio (A/B) with Goniophotometer
[0038] Herein, first the angle of incidence and the light receiving
angle will be described. When measuring the ratio with the
goniophotometer in the exemplary embodiment, the angle of incidence
is set to -45.degree., and this is because high measurement
sensitivity is obtained with respect to an image with a wide range
of glossiness.
[0039] In addition, the light receiving angle is set to -30.degree.
and to +30.degree. because the measurement sensitivity is highest
when evaluating an image with a brilliance and an image with no
brilliance.
[0040] Next, a method of measuring the ratio (A/B) will be
described.
[0041] In the exemplary embodiment, when measuring the ratio (A/B),
first, a "solid image" is formed with the following method. A
developer unit of a DocuCentre-III C7600 manufactured by Fuji Xerox
Co., Ltd. is filled with a developer that is a sample, and a solid
image having a toner applied amount of 4.5 g/cm.sup.2 is formed on
a recording sheet (OK TopCoat plus, manufactured by Oji Paper Co.,
Ltd.) at a fixing temperature of 190.degree. C. and a fixing load
of 4.0 kg/cm.sup.2. The "solid image" indicates an image having
coverage rate of 100%.
[0042] The incident light at an angle of incidence of -45.degree.
with respect to the solid image is applied to an image part of the
formed solid image, and a reflectance A at a light receiving angle
of +30.degree. and a reflectance B at a light receiving angle of
-30.degree. are measured by using a spectral varied angle
color-difference meter GC5000L as a goniophotometer manufactured by
Nippon Denshoku Industries Co., Ltd. Each of the reflectance A and
the reflectance B is measured regarding the light having a
wavelength of 400 nm to 700 nm at intervals of 20 nm, and defined
as an average of the reflectances at respective wavelengths. The
ratio (A/B) is calculated from these measurement results.
[0043] From the viewpoint of satisfying the above-described ratio
(A/B), the brilliant toner according to the exemplary embodiment
preferably satisfies the following requirements (1) and (2).
[0044] (1) The toner particles have an average equivalent circle
diameter D longer than an average maximum thickness C.
[0045] (2) When cross sections of toner particles in a thickness
direction are observed, a rate of a metallic pigment in which an
angle between a long axis direction of the toner particles in the
cross section and a long axis direction of the metallic pigment is
from -30.degree. to +30.degree. is 60% or greater with respect to
the total metallic pigments that are observed.
[0046] Herein, FIG. 2 shows a cross-sectional view schematically
showing an example of toner particles satisfying the requirements
(1) and (2) described above. The schematic view shown in FIG. 2 is
a cross-sectional view of the toner particles in a thickness
direction thereof.
[0047] A toner particle 2 shown in FIG. 2 is a long and flake shape
toner particle having an equivalent circle diameter larger than a
thickness L, and contains flake-shape metallic pigments 4.
[0048] As described above, in the exemplary embodiment, the flake
shape toner particles are arranged so that the flake surface sides
thereof face the surface of the recording medium (direction close
to the parallel direction) due to the physical pressure from the
fixing member in the fixing step.
[0049] Therefore, among the flake shape metallic pigments contained
in the toner particle, metallic pigment that satisfy "an angle
between a long axis direction of the toner in the cross section and
a long axis direction of the brilliant pigment particle is from
-30.degree. to +30.degree." described in the requirement (2) are
arranged so that the surface side that provides the maximum area
faces the surface of the recording medium (direction close to the
parallel direction). When the image formed in this manner is
irradiated with light, the proportion of the brilliant pigment
particles that causes diffuse reflection of the incident light is
suppressed, and thus the above-described range of the ratio (A/B)
is easily achieved.
[0050] In the exemplary embodiment, the moisture content of the
Ti-containing particles is preferably from 1% by weight to 10% by
weight.
[0051] When the Ti-containing particles having the moisture content
of the range described above are used, an image having a high
brilliance is obtained even after deterioration of the toner,
compared to a case where the moisture content is beyond the range
described above. The reason thereof is not clear, but it is assumed
that, when the Ti-containing particles contain a specific quantity
of moisture, a high charge exchanging property with low resistance
is obtained and the charge of the toner particles easily leaks,
compared to a case where the moisture content described above is
smaller than the range described above. Therefore, as described
above, an electrostatic adhesive force between the toner particles
is reduced and the toner particles are hardly aggregated, and an
image having a high brilliance is obtained even after deterioration
of the toner.
[0052] In addition, it is considered that, when the moisture
content of the Ti-containing particles is in the range described
above, the aggregation of the Ti-containing particles caused by the
moisture hardly occurs, compared to a case where the moisture
content described above is larger than the range described above.
Accordingly, since the Ti-containing particles are externally
evenly added to the surface of the toner particles, it is assumed
that the effect of the reduction of the electrostatic adhesive
force due to the Ti-containing particles is easily obtained, and as
a result, an image having a high brilliance is obtained even after
deterioration of the toner.
[0053] Herein, the moisture content of the Ti-containing particles
is measured with the following method.
[0054] The moisture content thereof is measured by using a heat
analysis device DTG-60AH (manufactured by Shimadzu Corporation). In
the pretreatment, vacuum drying is performed at 100.degree. C. for
24 hours, for example. In detail, for example, the pressure is
reduced to -0.1 MPa and drying is performed at 100.degree. C. for
24 hours with VOS-301SD (manufactured by TOKYO RIKAKIKIKAI Co.,
Ltd.) After that, after holding the particles under the nitrogen
atmosphere (30 ml/min) at 30.degree. C. for 1 hour, the temperature
is increased at a rate of temperature rise of 30.degree. C./min,
and a rate of the moisture quantity with respect to all of the
Ti-containing particles is acquired from loss on heating at a
temperature of 30.degree. C. to 250.degree. C. and used as the
moisture content (% by weight).
[0055] The moisture content of the Ti-containing particles is more
preferably from 2% by weight to 8% by weight and even more
preferably from 3% by weight to 6% by weight.
[0056] As a method of controlling the moisture content of the
Ti-containing particles, the following method is used. In detail,
for example, there is a method of controlling the moisture content
by preparing the Ti-containing particles with a wet-type preparing
method and, changing the drying temperature or the surface
processing conditions.
[0057] In the exemplary embodiment, a number average particle size
of the Ti-containing particles is preferably from 7 nm to 50
nm.
[0058] When the Ti-containing particles having the number average
particle size of the range described above are used, an image
having a high brilliance is obtained even after deterioration of
the toner, compared to a case where the number average particle
size is greater than the range described above. The reason thereof
is not clear, but when the number average particle size of the
Ti-containing particles is in the range described above, the
Ti-containing particles are easily and strongly attached to and are
easily embedded in the toner particles, compared to a case where
the number average particle size is greater than the range
described above. Accordingly, it is assumed that the effect of the
reduction of the electrostatic adhesive force due to the
Ti-containing particles is easily obtained, and as a result, an
image having a high brilliance is obtained even after deterioration
of the toner.
[0059] As the number average particle size of the Ti-containing
particles is small, the Ti-containing particles are easily and
strongly attached to the toner particles, but the number average
particle size thereof is preferably equal to or greater than 7 nm,
from a viewpoint of practical availability.
[0060] Herein, the number average particle size of the
Ti-containing particles is measured with the following method.
[0061] In detail, the surface of toner particles is observed with
an electron scanning microscope (SEM (S4700) manufactured by
Hitachi, Ltd.) with a magnification power of 40000, images of 100
Ti-containing particles existing on an outer periphery of the toner
particles is analyzed by using an image processing analysis
software WinRoof (manufactured by MITANI CORPORATION), an average
of the obtained equivalent circle diameters of the Ti-containing
particles is obtained, and the number average particle size thereof
is calculated.
[0062] The number average particle size of the Ti-containing
particles is more preferably from 10 nm to 30 nm.
[0063] In the exemplary embodiment, the Ti-containing particles
preferably have a tabular shape.
[0064] When the tabular Ti-containing particles are used, an image
having a high brilliance is obtained even after deterioration of
the toner, compared to a case where the Ti-containing particles
which do not have a tabular shape (for example, spherical
Ti-containing particles) are used. The reason thereof is not clear,
but when the Ti-containing particles have a tabular shape, the
Ti-containing particles have a large contact area with the toner
particles and are easily and strongly attached to the toner
particles. Accordingly, it is assumed that the effect of the
reduction of the electrostatic adhesive force due to the
Ti-containing particles is easily obtained, and as a result, an
image having a high brilliance is obtained even after deterioration
of the toner.
[0065] The phrase "Ti-containing particles have a tabular shape"
herein means that a ratio (hereinafter, referred to as "ratio of
height/long axis" in some cases) of the height of the Ti-containing
particles (length of shortest axis among the axis orthogonal to the
long axis) with respect to the length of the long axis of the
Ti-containing particles (length of longest axis) is equal to or
smaller than 0.8.
[0066] The length of the long axis and the height of the
Ti-containing particles are acquired by observing with the SEM and
analyzing with the image processing analysis software, in the same
manner as in the measurement of the number average particle size of
the Ti-containing particles. In detail, the "ratios of height/long
axis" of 100 Ti-containing particles existing on an outer periphery
of the toner particles are acquired from the images and the average
thereof is obtained.
[0067] The value of the "ratio of height/long axis" of the
Ti-containing particles is preferably equal to or smaller than 0.7,
and more preferably from 0.1 to 0.5. When the "ratio of height/long
axis" of the Ti-containing particles is equal to or greater than
0.1, the contact area of each particle of the Ti-containing
particles and the toner surface becomes great, and therefore it is
advantageous to easily evenly disperse on the toner surface. In
addition, when the "ratio of height/long axis" of the Ti-containing
particles is equal to or smaller than 0.7, the Ti-containing
particles are easily strongly attached to the toner particles and
the effect of the reduction of the electrostatic adhesive force due
to the Ti-containing particles is easily exhibited, compared to a
case where the ratio thereof is greater than 0.7.
[0068] As a method of controlling the shape of the Ti-containing
particles and adjusting the value of the "ratio of height/long
axis", a method of selecting a composition with which a target
shape is obtained, is used, for example. In addition, in a case of
using titanium oxide particles as the Ti-containing particles, for
example, a method of controlling a crystalline structure and
controlling the shape of the Ti-containing particles is also
used.
[0069] The value of the ratio of height/long axis of the
Ti-containing particles is greater than the value of a ratio (C/D)
of the average maximum thickness C and the average equivalent
circle diameter D of the toner particles.
[0070] The value of the ratio of height/long axis of the
Ti-containing particles is in a range of 1.1 times to 25 times the
value of the ratio (C/D) of the average maximum thickness C and the
average equivalent circle diameter D of the toner particles.
[0071] Hereinafter, the toner according to the exemplary embodiment
will be described.
[0072] The toner according to the exemplary embodiment includes the
toner particles and the Ti-containing particles, and if necessary,
may include other components.
[0073] Toner Particles
[0074] The toner particles are configured to include a binder resin
and a flake shape metallic pigment, and if necessary, may include a
release agent and other additives.
[0075] Metallic Pigment
[0076] As the metallic pigment, metallic powder such as aluminum,
brass, bronze, nickel, stainless steel, zinc or the like is used,
and there is no particular limitation as long as it is a pigment
containing metal. The metallic pigment may be used alone or in
combination with two or more kinds thereof.
[0077] Among the metallic pigments, particularly from a viewpoint
of availability and easy flattening of the toner particles,
aluminum is most preferable. The surface of the metallic pigment
may be coated with silica particles, an acrylic resin, or a
polyester resin.
[0078] The content of the metallic pigment with respect to the
toner particles is, for example, preferably from 1 part by weight
to 70 parts by weight and more preferably from 5 parts by weight to
50 parts by weight, with respect to 100 parts by weight of the
binder resin which will be described later.
[0079] As described above, the metallic pigment has a flake
shape.
[0080] The value of the ratio (C/D) of the metallic pigment is
preferably 0.700 or less, more preferably from 0.005 to 0.1, and
even more preferably from 0.01 to 0.1. When the ratio (C/D) of the
metallic pigment is equal to or greater than 0.005, it is
advantageous because the strong resistance is obtained with respect
to stirring stress when granulating the toner. In addition, when
the ratio (C/D) of the metallic pigment is equal to or smaller than
0.700, a high brilliance is easily obtained, compared to a case
where the ratio thereof is greater than 0.700.
[0081] Binder Resin
[0082] Examples of the other binder resins include a homopolymer of
a monomer such as styrenes (for example, styrene, p-chlorostyrene,
.alpha.-methyl styrene, or the like), (meth)acrylic esters (for
example, methyl acrylate, ethyl acrylate, n-propyl acrylate,
n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl
methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl
methacrylate, 2-ethylhexyl methacrylate, or the like), ethylenic
unsaturated nitriles (for example, acrylonitrile,
methacrylonitrile, or the like), vinyl ethers (for example, vinyl
methyl ether, vinyl isobutyl ether, or the like), vinyl ketones
(for example, vinyl methyl ketone, vinyl ethyl ketone, vinyl
isopropenyl ketone, or the like), olefins (for example, ethylene,
propylene, butadiene, or the like), or a vinyl resin formed of a
copolymer obtained by combining two or more kinds of the
monomers.
[0083] Examples of the binder resin include a non-vinyl resin such
as an epoxy resin, a polyester resin, a polyurethane resin, a
polyamide resin, a cellulose resin, a polyether resin, and modified
rosin, a mixture of these and the vinyl resin, or a graft polymer
obtained by polymerizing the vinyl monomer under coexistence
thereof.
[0084] These binder resins may be used alone or in combination with
two or more kinds thereof.
[0085] As the binder resin, a polyester resin is preferable.
[0086] As the polyester resin, a well-known polyester resin is
used, for example.
[0087] Examples of the polyester resin include condensation
polymers of polyvalent carboxylic acids and polyols. A commercially
available product or a synthesized product may be used as the
polyester resin.
[0088] Examples of the polyvalent carboxylic acid include aliphatic
dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid,
fumaric acid, citraconic acid, itaconic acid, glutaconic acid,
succinic acid, alkenyl succinic acid, adipic acid, and sebacic
acid), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic
acid), aromatic dicarboxylic acids (e.g., terephthalic acid,
isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid),
anhydrides thereof, or lower alkyl esters (having, for example,
from 1 to 5 carbon atoms) thereof. Among these, for example,
aromatic dicarboxylic acids are preferably used as the polyvalent
carboxylic acid.
[0089] As the polyvalent carboxylic acid, a tri- or higher-valent
carboxylic acid employing a crosslinked structure or a branched
structure may be used in combination together with a dicarboxylic
acid. Examples of the tri- or higher-valent carboxylic acid include
trimellitic acid, pyromellitic acid, anhydrides thereof, or lower
alkyl esters (having, for example, from 1 to 5 carbon atoms)
thereof.
[0090] The polyvalent carboxylic acids may be used alone or in
combination of two or more kinds thereof.
[0091] Examples of the polyol include aliphatic diols (e.g.,
ethylene glycol, diethylene glycol, triethylene glycol, propylene
glycol, butanediol, hexanediol, and neopentyl glycol), alicyclic
diols (e.g., cyclohexanediol, cyclohexanedimethanol, and
hydrogenated bisphenol A), and aromatic diols (e.g., ethylene oxide
adduct of bisphenol A and propylene oxide adduct of bisphenol A).
Among these, for example, aromatic diols and alicyclic diols are
preferably used, and aromatic diols are more preferably used as the
polyol.
[0092] As the polyol, a tri- or higher-valent polyol employing a
crosslinked structure or a branched structure may be used in
combination together with a diol. Examples of the tri- or
higher-valent polyol include glycerin, trimethylolpropane, and
pentaerythritol.
[0093] The polyols may be used alone or in combination of two or
more kinds thereof.
[0094] A glass transition temperature (Tg) of the polyester resin
is preferably from 50.degree. C. to 80.degree. C., and more
preferably from 50.degree. C. to 65.degree. C.
[0095] The glass transition temperature is acquired by a DSC curve
obtained by differential scanning calorimetry (DSC), and more
specifically, is acquired by "extrapolation glass transition
starting temperature" disclosed in a method of acquiring the glass
transition temperature of JIS K7121-1987 "Testing Methods for
Transition Temperature of Plastics".
[0096] A weight average molecular weight (Mw) of the polyester
resin is preferably from 5,000 to 1,000,000, and more preferably
from 7,000 to 500,000.
[0097] The number average molecular weight (Mn) of the polyester
resin is preferably from 2,000 to 100,000.
[0098] The molecular weight distribution Mw/Mn of the polyester
resin is preferably from 1.5 to 100, and more preferably from 2 to
60.
[0099] The weight average molecular weight and the number average
molecular weight are measured by gel permeation chromatography
(GPC). The molecular weight measurement by GPC is performed with a
THF solvent using HLC-8120 GPC, which is GPC manufactured by Tosoh
Corporation as a measurement device by using TSKgel Super HM-M (15
cm), which is a column manufactured by Tosoh Corporation. The
weight average molecular weight and the number average molecular
weight are calculated using a calibration curve of molecular weight
created with a monodisperse polystyrene standard sample from
results of this measurement.
[0100] The polyester resin is obtained with a well-known preparing
method. Specific examples thereof include a method of conducting a
reaction at a polymerization temperature set to 180.degree. C. to
230.degree. C., if necessary, under reduced pressure in the
reaction system, while removing water or an alcohol generated
during condensation.
[0101] When monomers of the raw materials are not dissolved or
compatibilized under a reaction temperature, a high-boiling-point
solvent may be added as a solubilizing agent to dissolve the
monomers. In this case, a polycondensation reaction is conducted
while distilling away the solubilizing agent. When a monomer having
poor compatibility is present in a copolymerization reaction, the
monomer having poor compatibility and an acid or an alcohol to be
polycondensed with the monomer may be previously condensed and then
polycondensed with the major component.
[0102] The content of the binder resin is preferably from 40% by
weight to 95% by weight, more preferably from 50% by weight to 90%
by weight, and even more preferably from 60% to 85% by weight, with
respect to the entire toner particles.
[0103] Release Agent
[0104] Examples of the release agent include hydrocarbon-based
waxes; natural waxes such as carnauba wax, rice wax, and candelilla
wax; synthetic or mineral/petroleum-based waxes such as montan wax;
and ester-based waxes such as fatty acid esters and montanic acid
esters. The release agent is not limited thereto.
[0105] The melting temperature of the release agent is preferably
from 50.degree. C. to 110.degree. C., and more preferably from
60.degree. C. to 100.degree. C.
[0106] The melting temperature is obtained from "melting peak
temperature" described in the method of obtaining a melting
temperature in JIS K7121-1987 "Testing methods for transition
temperatures of plastics", from a DSC curve obtained by
differential scanning calorimetry (DSC).
[0107] The content of the release agent is, for example, preferably
from 1% by weight to 20% by weight, and more preferably from 5% by
weight to 15% by weight with respect to the entire toner
particles.
[0108] Other Additives
[0109] Examples of other additives include known additives such as
a magnetic material, a charge-controlling agent, and an inorganic
powder. The toner particles include these additives as internal
additives.
[0110] In addition, as the other additives, the other colorant
other than the metallic pigment may be included. As the other
colorant, a well-known colorant is used, and the colorant is
selected depending on a desirable color.
[0111] Characteristics of Toner Particles
[0112] The toner particles may be toner particles having a
single-layer structure, or toner particles having a so-called
core/shell structure composed of a core (core particle) and a
coating layer (shell layer) coated on the core.
[0113] Here, toner particles having a core/shell structure is
preferably composed of, for example, a core containing a binder
resin, and if necessary, other additives such as a colorant and a
release agent and a coating layer containing a binder resin.
[0114] Average Maximum Thickness C and Average Equivalent Circle
Diameter D of Toner Particles
[0115] As described above, the toner particles have a flake shape.
That is, the value of the average maximum thickness C is smaller
than the value of the average equivalent circle diameter D.
[0116] In addition, the value of the ratio (C/D) of the toner
particles is preferably equal to or smaller than 0.700, more
preferably from 0.001 to 0.500, even more preferably from 0.010 to
0.200, and particularly preferably from 0.050 to 0.100. When the
ratio (C/D) is 0.001 or greater, toner particle strength is secured
and a fracture that is caused due to a stress in the image
formation is thus prevented, whereby a reduction in charges that is
caused by exposure of the pigment from the toner particles, and
fogging that is caused as a result thereof are prevented.
Meanwhile, when the ratio (C/D) is equal to or smaller than 0.700,
a high brilliance is easily obtained, compared to a case where the
ratio thereof is greater than 0.700.
[0117] Angle Between Long Axis Direction of Toner Particles in
Cross Section and Long Axis Direction of Brilliant Pigment
Particles
[0118] As shown in the requirement (2), when cross sections of
toner particles in a thickness direction are observed, the rate
(based on the number) of the metallic pigment in which an angle
between a long axis direction of the toner particles in the cross
section and a long axis direction of the metallic pigment is from
-30.degree. to +30.degree. is preferably 60% or greater of the
total number of metallic pigment particles that are observed.
Furthermore, the rate is more preferably from 70% to 95%, and
particularly preferably from 80% to 90% of the total number of
metallic pigment particles that are observed.
[0119] When the rate described above is equal to or greater than
60%, an excellent brilliance is obtained.
[0120] Herein, the observation method of the cross sections of
toner particles will be described.
[0121] Toner is embedded using a bisphenol A type liquid epoxy
resin and a hardening agent, and then a cut sample is prepared.
Then, the cut sample is cut by using a cutter using a diamond knife
(using LEICA Ultramicrotome (manufactured by Hitachi
High-Technologies Corporation) in the exemplary embodiment) at
-100.degree. C., and an observation sample is prepared. With this
observation sample, the cross sections of the toner particles are
observed using a transmission electron microscope (TEM) at a
magnification of about 5000-fold magnification. With the observed
1000 toners particles, the number of metallic pigments in which the
angle between the long axis direction of the toner particles in
cross section and the long axis direction of the metallic pigment
is from -30.degree. C. to +30.degree. C., is counted using image
analysis software, and the proportion thereof is calculated.
[0122] The "long axis direction of the toner particles in the cross
section" indicates a direction perpendicular to the thickness
direction of the toner particles having the average equivalent
circle diameter D larger than the average maximum thickness C. The
"long axis direction of the metallic pigment" indicates a length
direction of the metallic pigment.
[0123] Volume Average Particle Size of Toner Particles
[0124] The volume average particle size of the toner particles is
preferably from 1 .mu.m to 30 .mu.m, and more preferably from 3
.mu.m to 20 .mu.m. When the toner particles have a flake shape as
in the toner particles of the exemplary embodiment, the value of
the volume average particle size represents a volume average value
of an equivalent spherical diameter.
[0125] In detail, regarding the volume average particle size
D.sub.50v, cumulative distributions by volume and by number are
drawn from the side of the smallest size on the basis of particle
size ranges (channels) separated based on the particle size
distribution measured by a measuring machine such as a Multisizer
II (manufactured by Beckman Coulter Inc.). The particle size when
the cumulative percentage becomes 16% is defined as that
corresponding to a volume D.sub.16v and a number D.sub.16p. The
particle size when the cumulative percentage becomes 50% is defined
as that corresponding to a volume D.sub.50v and a number D.sub.50p,
and the particle size when the cumulative percentage becomes 84% is
defined as that corresponding to a volume D.sub.84v and a number
D.sub.84p. Using these, a volume average particle size distribution
index (GSDv) is calculated as (D.sub.84v/D.sub.16v).sup.1/2.
[0126] Ti-Containing Particles
[0127] There is no particular limitation for the Ti-containing
particles as long as the particles contain Ti elements and have a
particular shape, and examples thereof include titanium oxide,
titanium carbide, titanate, (magnesium salts, calcium salts,
strontium salts, barium salts), and the like.
[0128] Specific examples of the Ti-containing particles include
titanium oxide such as TiO.sub.2 (titania), and TiO(OH).sub.2
(metatitanic acid); titanium carbide such as TiC (titanium
carbide); titanate such as CaTiO.sub.3 or SrTiO.sub.3; and the
like.
[0129] Among the Ti-containing particles, TiO(OH).sub.2 is
preferable from a viewpoint that the "ratio of height/long axis" of
the Ti-containing particles is easily reduced, TiO.sub.2 is
preferable from a viewpoint that the number average particle size
is easily set in the range described above, and titanate (among
these, particularly SrTiO.sub.3) is preferable from a viewpoint
that an high charge exchanging property is excellent.
[0130] The added amount of the Ti-containing particles is, for
example, in a range of 0.1 part by weight to 1.5 parts by weight,
is preferably from 0.1 part by weight to 0.8 parts by weight, and
more preferably from 0.2 part by weight to 0.4 part by weight, with
respect to 100 parts by weight of the toner particles. When the
added amount of the Ti-containing particles is in the range
described above, the effect of the reduction of the electrostatic
adhesive force between the toner particles is easily obtained,
compared to a case where the added amount thereof is smaller than
the range described above, and the charge leakage of the toner
surface is evenly promoted, compared to a case where the added
amount thereof is greater than the range described above.
[0131] Other External Additive
[0132] The toner according to the exemplary embodiment may include
other external additives.
[0133] Examples of other external additives include inorganic
particles which does not contain the Ti element, and specific
examples thereof include SiO.sub.2, Al.sub.2O.sub.3, CuO, ZnO,
SnO.sub.2, CeO.sub.2, Fe.sub.2O.sub.3, MgO, BaO, CaO, K.sub.2O,
Na.sub.2O, ZrO.sub.2, CaO.SiO.sub.2, Al.sub.2O.sub.3.2SiO.sub.2,
CaCO.sub.3, MgCO.sub.3, BaSO.sub.4, MgSO.sub.4, and the like.
[0134] Surfaces of the inorganic particles used as the other
external additive are preferably subjected to a hydrophobizing
treatment. The hydrophobizing treatment is performed by, for
example, dipping the inorganic particles in a hydrophobizing agent.
The hydrophobizing agent is not particularly limited and examples
thereof include a silane coupling agent, silicone oil, a titanate
coupling agent, and an aluminum coupling agent. These may be used
alone or in combination of two or more kinds thereof.
[0135] Generally, the amount of the hydrophobizing agent is, for
example, from 1 part by weight to 10 parts by weight with respect
to 100 parts by weight of the inorganic particles.
[0136] In addition to the inorganic particles, examples of the
other external additive also include resin particles (resin
particles such as polystyrene, PMMA, and melamine resin) and a
cleaning aid (e.g., metal salt of higher fatty acid represented by
zinc stearate, and fluorine-based polymer particles).
[0137] Toner Preparing Method
[0138] Next, a method of preparing a toner according to the
exemplary embodiment will be described.
[0139] The toner according to the exemplary embodiment is obtained
by externally adding an external additive to toner particles after
preparing of the toner particles.
[0140] The method of preparing toner particles is not particularly
limited, and toner particles are prepared by a known method such as
a dry method, e.g., a kneading and pulverizing method or a wet
method, e.g., an emulsion aggregating method and a dissolution and
suspension method.
[0141] The kneading and pulverizing method is a method of mixing
each material such as the metallic pigment and the like and then
melting and kneading the material using a kneader, an extruder or
the like, performing coarse pulverizing of the obtained melted and
kneaded material, and then performing pulverization using a jet
mill, and obtaining toner particles having a toner diameter in a
target range by a wind classifier.
[0142] In more detail, the kneading and pulverizing method is
divided into a kneading step of kneading a toner forming material
including the metallic pigment and the binder resin, and a
pulverization step of pulverizing the kneaded material. If
necessary, the method may include a cooling step of cooling the
kneaded material formed by the kneading step, or another step.
[0143] The dissolution and suspension method is a method of
obtaining toner particles including: subjecting a liquid in which a
material containing a binder resin, a metallic pigment, and if
necessary other optional components such as a release agent is
dissolved or dispersed in a solvent in which the binder resin is
soluble to granulation in an inorganic dispersant-containing
aqueous medium; and removing the solvent.
[0144] Examples of other components that are used in the
dissolution and suspension method include various components such
as a charge-controlling agent and organic particles, as well as a
release agent.
[0145] In the exemplary embodiment, an emulsion aggregating method
may be used in which the shape and the particle size of toner
particles are easily controlled and the control range in the
structure of toner particles such as a core-shell structure is also
wide. Hereinafter, a method of preparing toner particles using an
emulsion aggregating method will be described in detail.
[0146] The emulsion aggregating method according to the exemplary
embodiment has an emulsification step of forming resin particles
(emulsification particles) or the like by emulsifying raw materials
constituting the toner particles, an aggregation step of forming
aggregates of the resin particles, and a coalescence step of
coalescing the aggregates.
[0147] Emulsification Step
[0148] A resin particle dispersion may be prepared using a general
polymerization method such as an emulsion polymerization method, a
suspension polymerization method, or a dispersion polymerization
method. Otherwise, a resin particle dispersion may be prepared
through emulsification by applying a shear force to a solution
obtained by mixing an aqueous medium with a binder resin using a
dispersing machine. In this case, particles may be formed by
reducing the viscosity of the resin component by heating. In
addition, a dispersant may be used in order to stabilize the
dispersed resin particles. Furthermore, when a resin is soluble in
an oily solvent having a relatively low solubility to water, the
resin is dissolved in the solvent so that particles thereof are
dispersed in the water together with a dispersant or a
polyelectrolyte, and then heating or decompression is performed to
evaporate the solvent, thereby preparing a resin particle
dispersion.
[0149] Examples of the aqueous medium include water such as
distilled water and ion exchange water; and alcohols. Water is
preferably used.
[0150] Examples of the dispersant that is used in the
emulsification step include water-soluble polymers such as
polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxyethyl
cellulose, carboxymethyl cellulose, sodium polyacrylate, and sodium
polymethacrylate; surfactants such as anionic surfactants, e.g.,
sodium dodecylbenzenesulfonate, sodium octadecylsulfate, sodium
oleate, sodium laurate, and potassium stearate, cationic
surfactants, e.g., laurylamine acetate, stearyl amine acetate, and
lauryl trimethyl ammonium chloride, zwitterionic surfactants, e.g.,
lauryl dimethyl amine oxide, and nonionic surfactants, e.g.,
polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether,
and polyoxyethylene alkylamine; and inorganic salts such as
tricalcium phosphate, aluminum hydroxide, calcium sulfate, calcium
carbonate, and barium carbonate.
[0151] Examples of the dispersing machine that is used in the
preparation of the emulsified liquid include a homogenizer, a
homomixer, a pressure kneader, an extruder, and a media-dispersing
machine. The size of the resin particles is preferably 1.0 .mu.m or
less, more preferably from 60 nm to 300 nm, and even more
preferably from 150 nm to 250 nm in terms of the average particle
size (volume average particle size). When the size is 60 nm or
greater, the resin particles easily become unstable in the
dispersion, and thus the resin particles may easily aggregate. When
the size is 1.0 .mu.m or less, the particle size distribution of
the toner may be narrowed.
[0152] In the preparation of a release agent dispersion, a release
agent is dispersed in water, together with an ionic surfactant or a
polyelectrolyte such as a polymer acid or a polymer base, and then
a dispersion treatment is performed using a homogenizer or a
pressure discharge-type dispersing machine with which a strong
shear force is applied, simultaneously with heating to a
temperature that is not lower than the melting temperature of the
release agent. A release agent dispersion is obtained through such
a treatment. In the dispersion treatment, an inorganic compound
such as polyaluminum chloride may be added to the dispersion.
Examples of the preferable inorganic compound include polyaluminum
chloride, aluminum sulfate, highly basic polyaluminum chloride
(BAC), polyaluminum hydroxide, and aluminum chloride. Among these,
polyaluminum chloride, aluminum sulfate, and the like are
preferable.
[0153] Through the dispersion treatment, a release agent dispersion
containing release agent particles having a volume average particle
size of 1 .mu.m or less is obtained. More preferably, the volume
average particle size of the release agent particles is from 100 nm
to 500 nm.
[0154] When the volume average particle size is 100 nm or greater,
though it is also affected by the characteristics of the binder
resin to be used, but generally, the release agent component is
easily incorporated in the toner. When the volume average particle
size is 500 nm or less, the release agent in the toner has a
superior dispersion state.
[0155] In order to prepare a metallic pigment dispersion, a known
dispersion method may be used and a general dispersion unit such as
a rotary shearing-type homogenizer, a ball mill having media, a
sand mill, a Dyno mill, or an Ultimizer may be employed, but there
are no limits to the dispersion unit. The metallic pigment is
dispersed in water, together with an ionic surfactant or a
polyelectrolyte such as a polymer acid or a polymer base. The
volume average particle size of the dispersed metallic pigment may
be 20 .mu.m or less. The volume average particle size is preferably
from 3 .mu.m to 16 .mu.m, since the metallic pigment is dispersed
well in the toner with no impairment in aggregability.
[0156] In addition, a metallic pigment and a binder resin may be
dispersed and dissolved to be mixed with each other in a solvent,
and dispersed in the water by phase inversion emulsification or
shearing emulsification, thereby preparing a dispersion of metallic
pigment coated with the binder resin.
[0157] Aggregation Step
[0158] In the aggregation step, a resin particle dispersion, a
metallic pigment dispersion, a release agent dispersion, and the
like are mixed to prepare a mixture, and heated to a temperature
that is not higher than the glass transition temperature of the
resin particles for aggregation, thereby forming aggregated
particles. In many cases, in order to form the aggregated
particles, the pH of the mixture is adjusted to acidic under
stirring. By virtue of the above stirring conditions, the ratio
(C/D) may be adjusted in a preferable range. More specifically, in
the aggregated particle forming stage, when rapid stirring and
heating are performed, the ratio (C/D) may be reduced, and when the
stirring speed is reduced and the heating is performed at lower
temperature, the ratio (C/D) may be increased. The pH is preferably
from 2 to 7, at which an aggregating agent may also be effectively
used.
[0159] Furthermore, in the aggregation step, the release agent
dispersion may be added and mixed together with various dispersions
such as a resin particle dispersion at a time or several times.
[0160] As the aggregating agent, a di- or higher-valent metal
complex is preferably used, as well as a surfactant having an
opposite polarity to the polarity of the surfactant that is used as
the dispersant, and an inorganic metal salt. Since the amount of
the surfactant to be used may be reduced and the charging
characteristics are improved, a metal complex is particularly
preferably used.
[0161] As the inorganic metal salt, aluminum salts and polymers
thereof are particularly preferable. In order to obtain a narrower
particle size distribution, the valence of the inorganic metal salt
is more preferably divalent than monovalent, trivalent than
divalent, or tetravalent than trivalent, and further, in the case
of the same valences as each other, a polymer-type inorganic metal
salt polymer is more suitable.
[0162] In the exemplary embodiment, a polymer of tetravalent
inorganic metal salt including aluminum is preferably used to
obtain a narrow particle size distribution.
[0163] In addition, when the aggregated particles have a desired
particle size, the resin particle dispersion may be further added
(coating step) to prepare a toner having a configuration in which a
surface of a core aggregated particle is coated with a resin. In
this case, the release agent or the metallic pigment is not easily
exposed to the toner surface, and thus the configuration is
preferable from the viewpoint of charging properties or
developability. In the case of further addition, an aggregating
agent may be added or the pH may be adjusted before further
addition.
[0164] Coalescence Step
[0165] In the coalescence step, the progression of the aggregation
is stopped by increasing the pH of the suspension of the aggregated
particles to the range of 3 to 9 under stirring conditions based on
the aggregation step, and the aggregated particles are coalesced by
heating at a temperature that is not lower than the glass
transition temperature of the resin.
[0166] In addition, in the case of coating with the resin, the
resin is also coalesced and the core aggregated particles are
coated therewith. Regarding the heating time, the heating may be
performed to the extent that the coalescence is caused, and may be
performed for 0.5 hour to 10 hours.
[0167] After coalescence, cooling is performed to obtain coalesced
particles. In addition, in the cooling step, crystallization may be
promoted by lowering the cooling rate at around the glass
transition temperature of the resin (glass transition
temperature.+-.10.degree. C.), that is, so-called slow cooling.
[0168] The coalesced particles obtained by coalescence are
subjected to a solid-liquid separation step such as filtration, and
if necessary, a washing step and a drying step, and thus toner
particles are obtained.
[0169] The toner according to the exemplary embodiment is prepared
by, for example, adding and mixing the Ti-containing particles (and
if necessary, other external additives) with dry toner particles
that have been obtained. The mixing is preferably performed with,
for example, a V-blender, a Henschel mixer, a Lodige mixer, or the
like. Furthermore, if necessary, coarse toner particles may be
removed using a vibration sieving machine, a wind classifier, or
the like.
[0170] As described above, in the exemplary embodiment, since the
effect of the reduction of the electrostatic adhesive force is
obtained even when the Ti-containing particles are embedded in the
toner particles, the Ti-containing particles may be strongly
attached to the toner particles as the Ti-containing particles are
embedded.
[0171] Electrostatic Charge Image Developer
[0172] An electrostatic charge image developer according to the
exemplary embodiment includes at least the toner according to the
exemplary embodiment.
[0173] The electrostatic charge image developer according to the
exemplary embodiment may be a single-component developer including
only the toner according to the exemplary embodiment, or a
two-component developer obtained by mixing the toner with a
carrier.
[0174] The carrier is not particularly limited, and known carriers
are exemplified. Examples of the carrier include a coated carrier
in which surfaces of cores formed of a magnetic powder are coated
with a coating resin; a magnetic powder dispersion-type carrier in
which a magnetic powder is dispersed and blended in a matrix resin;
a resin impregnation-type carrier in which a porous magnetic powder
is impregnated with a resin.
[0175] The magnetic powder dispersion-type carrier, the resin
impregnation-type carrier, and the conductive particle
dispersion-type carrier may be carriers in which constituent
particles of the carrier are cores and coated with a coating
resin.
[0176] Examples of the magnetic powder include magnetic metal such
as iron, nickel, cobalt, and the like, and magnetic oxide such as
ferrite, magnetite, and the like.
[0177] Examples of the coating resin and the matrix resin include
polyethylene, polypropylene, polystyrene, polyvinyl acetate,
polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl
ether, polyvinyl ketone, a vinyl chloride-vinyl acetate copolymer,
a styrene-acrylic acid copolymer, a straight silicone resin
configured to include an organosiloxane bond or a modified product
thereof, a fluorine resin, polyester, polycarbonate, a phenol
resin, and an epoxy resin.
[0178] The coating resin and the matrix resin may contain other
additives such as a conductive material.
[0179] Examples of the conductive materials include particles of
metals such as gold, silver, and copper, carbon black particles,
titanium oxide particles, zinc oxide particles, tin oxide
particles, barium sulfate particles, aluminum borate particles, and
potassium titanate particles.
[0180] Here, a coating method using a coating layer forming
solution in which a coating resin, and if necessary, various
additives are dissolved in an appropriate solvent is used to coat
the surface of a core with the coating resin. The solvent is not
particularly limited, and may be selected in consideration of the
coating resin to be used, coating suitability, and the like.
[0181] Specific examples of the resin coating method include a
dipping method of dipping cores in a coating layer forming
solution, a spraying method of spraying a coating layer forming
solution to surfaces of cores, a fluid bed method of spraying a
coating layer forming solution in a state in which cores are
allowed to float by flowing air, and a kneader-coater method in
which cores of a carrier and a coating layer forming solution are
mixed with each other in a kneader-coater and the solvent is
removed.
[0182] The mixing ratio (weight ratio) between the toner and the
carrier in the two-component developer is preferably from 1:100 to
30:100 (toner: carrier), and more preferably from 3:100 to
20:100.
[0183] Image Forming Apparatus and Image Forming Method
[0184] An image forming apparatus and an image forming method
according to the exemplary embodiment will be described.
[0185] The image forming apparatus according to the exemplary
embodiment is provided with an image holding member, a charging
unit that charges a surface of the image holding member, an
electrostatic charge image forming unit that forms an electrostatic
charge image on a charged surface of the image holding member, a
developing unit that contains an electrostatic charge image
developer and develops the electrostatic charge image formed on the
surface of the image holding member with the electrostatic charge
image developer to forma toner image, a transfer unit that
transfers the toner image formed on the surface of the image
holding member onto a surface of a recording medium, and a fixing
unit that fixes the toner image transferred onto the surface of the
recording medium. As the electrostatic charge image developer, the
electrostatic charge image developer according to the exemplary
embodiment is applied.
[0186] In the image forming apparatus according to the exemplary
embodiment, an image forming method (image forming method according
to the exemplary embodiment) including a charging step of charging
a surface of an image holding member, an electrostatic charge image
forming step of forming an electrostatic charge image on a charged
surface of the image holding member, a developing step of
developing the electrostatic charge image formed on the surface of
the image holding member with the electrostatic charge image
developer according to the exemplary embodiment to form a toner
image, a transfer step of transferring the toner image formed on
the surface of the image holding member onto a surface of a
recording medium, and a fixing step of fixing the toner image
transferred onto the surface of the recording medium is
performed.
[0187] As the image forming apparatus according to the exemplary
embodiment, a known image forming apparatus is applied, such as a
direct transfer-type apparatus that directly transfers a toner
image formed on a surface of an image holding member onto a
recording medium; an intermediate transfer-type apparatus that
primarily transfers a toner image formed on a surface of an image
holding member onto a surface of an intermediate transfer member,
and secondarily transfers the toner image transferred onto the
surface of the intermediate transfer member onto a surface of a
recording medium; an apparatus that is provided with a cleaning
unit that cleans, after transfer of a toner image, a surface of an
image holding member before charging; or an apparatus that is
provided with an erasing unit that irradiates, after transfer of a
toner image, a surface of an image holding member with erasing
light before charging for erasing.
[0188] In the case of an intermediate transfer-type apparatus, a
transfer unit is configured to have, for example, an intermediate
transfer member having a surface onto which a toner image is to be
transferred, a primary transfer unit that primarily transfers a
toner image formed on a surface of an image holding member onto the
surface of the intermediate transfer member, and a secondary
transfer unit that secondarily transfers the toner image
transferred onto the surface of the intermediate transfer member
onto a surface of a recording medium.
[0189] In the image forming apparatus according to the exemplary
embodiment, for example, a part including the developing unit may
have a cartridge structure (process cartridge) that is detachable
from the image forming apparatus. As the process cartridge, for
example, a process cartridge that accommodates the electrostatic
charge image developer according to the exemplary embodiment and is
provided with a developing unit is preferably used.
[0190] In the exemplary embodiment, it is desirable to form an
image by making the fixing member including a conductive material
contact with the toner image to fix the toner image to the surface
of the recording medium.
[0191] That is, in the image forming apparatus according to the
exemplary embodiment, it is desirable that the fixing unit include
a fixing member which includes a conductive material and contacts
the toner image and fixes the toner image onto the surface of the
recording medium.
[0192] In addition, in the image forming method according to the
exemplary embodiment, it is desirable that the fixing step is a
step of fixing the toner image onto the surface of the recording
medium by making the fixing member including a conductive material
contact with the toner image.
[0193] As described above, by making the fixing member including a
conductive material contact with the toner image to fix the toner
image to the surface of the recording medium, an image having a
high brilliance is obtained even after deterioration of the toner.
The reason thereof is not clear, but it is assumed that, since the
fixing member which contacts the toner particles in the upright
state includes the conductive material, the charge of the toner
particles is more easily eliminated, and the electrostatic adhesive
force between the toner particles is more easily reduced.
[0194] As the conductive material contained in the fixing member,
conductive (for example, volume resistivity of less than 10.sup.7
.OMEGA.cm, the same applies hereinafter) or semiconductive (for
example, volume resistivity of 10.sup.7 .OMEGA.cm to 10.sup.13
.OMEGA.cm, the same applies hereinafter) powder (powder formed of
particles having a primary particle diameter of less than 10 .mu.m
is desirable and powder formed of particles having a primary
particle diameter of equal to or less than 1 .mu.m is more
desirable) is used.
[0195] Although there is no particular limitation, but the specific
examples of the conductive material include carbon black (for
example, Ketjen black, acetylene black, or carbon black having an
oxidized surface), metal (for example, aluminum and nickel), a
metal oxide compound (for example, yttrium oxide or tin oxide), ion
conductive substances (for example, potassium titanate or lithium
chloride), a conductive polymer (for example, polyaniline,
polypyrrole, polysulfone, or polyacetylene), and the like.
[0196] The conductive material may be used alone or in combination
of two or more kinds thereof.
[0197] The added amount of the conductive material may be adjusted
so as to set surface resistivity of the surface of the fixing
member which contacts the toner image or volume resistivity of the
fixing member to desirable values.
[0198] The surface resistivity of the surface which contacts the
toner image is, for example, from
1.times.10.sup.9.OMEGA./.quadrature. to
1.times.10.sup.14.OMEGA./.quadrature., and the volume resistivity
of the fixing member is, for example, from 1.times.10.sup.8
.OMEGA.cm to 1.times.10.sup.13 .OMEGA.cm.
[0199] When the fixing member is an endless belt including a
surface layer and the conductive material is contained in the
surface layer, for example, the specific content of the conductive
material is from 1% by weight to 50% by weight, preferably from 2%
by weight to 40% by weight, and more preferably from 4% by weight
to 30% by weight with respect to total components configuring the
surface layer.
[0200] In the exemplary embodiment, an angle (hereinafter, referred
to as a "contact angle" in some cases) formed by a contact surface
of the fixing member at a position where the recording medium
starts to contact the fixing member (hereinafter, referred to as a
"contact start position" in some cases) in a direction opposite the
proceeding direction of the recording medium is preferably from
5.degree. to 20.degree. with respect to the recording medium.
[0201] That is, in the image forming apparatus according to the
exemplary embodiment, it is desirable that the contact angle of the
fixing unit be in the range described above.
[0202] In addition, in the image forming method according to the
exemplary embodiment, it is desirable that the fixing step be a
step of fixing the toner image onto the recording medium so that
the contact angle is in the range described above.
[0203] As shown in FIG. 6, the "contact surface of the fixing
member at the contact start position" herein is defined as a
surface S obtained by linking a contact start position P at which a
surface S.sub.1 of the fixing member and a surface S.sub.2 of the
recording medium start to contact with each other, and a position R
of the surface of the fixing member corresponding to a position Q
which is 1 cm separated from the contact start position P to the
side opposite the proceeding direction A of the recording medium.
An angle .theta. formed by the surface S and the surface S.sub.2 of
the recording medium is the "contact angle".
[0204] When the contact angle described above is in the range
described above, an image having a high brilliance is obtained,
compared to a case where the contact angle is greater than the
range described above.
[0205] As described above, in the toner image before passing
through the contact start position (before contacting the fixing
member), plural toner particles are considered to be arranged in
the upright state due to the transfer electric field. The toner
particles arranged in the proceeding direction of the recording
medium successively pass through the contact start position. That
is, the toner particles existing downstream of the recording medium
in the proceeding direction (hereinafter, referred to as the
"downstream toner particles" in some cases) previously contact the
fixing member, and then the toner particles existing upstream of
the recording medium in the proceeding direction (hereinafter,
referred to as the "upstream toner particles" in some cases)
contact the fixing member.
[0206] At that time, it is considered that, when the gap of the
downstream toner particles and the upstream toner particles is
narrower than the length of the long axis of the toner particles,
the downstream toner particles lie due to the physical force of the
fixing member so as to contact the upstream toner particles, and
then the upstream toner particles lie due to the fixing member. As
described above, it is considered that, when the upstream toner
particles start to lie after the downstream toner particles contact
the upstream toner particles in the upright state, a fixed image in
which both of the toner particles are overlapped with each other is
consequently obtained.
[0207] With respect thereto, it is considered that, when the
contact angle is in the range described above, after the downstream
toner particles contact the fixing member and before the downstream
toner particles contact the upstream toner particles, the upstream
toner particles contact the fixing member and start to lie.
Accordingly, it is considered that, since the downstream toner
particles hardly contact the upstream toner particles, and even in
a case where the particles contact with each other, the downstream
toner particles contact the upstream toner particles which started
to lie, less amount of both of the toner particles are overlapped
with each other.
[0208] Hereinafter, an example of the fixing device in which the
contact angle is in the range described above will be described
with reference to the drawings, but there is no limitation
thereto.
[0209] FIG. 3 is a schematic diagram showing a configuration of a
fixing device 80 in which the contact angle is in the range
described above.
[0210] As shown in FIG. 3, the fixing device 80 is, for example,
configured to include a fixing belt module 86 including a heating
belt 84 as an example of the fixing member and a press roll 88
which is disposed to press by the heating belt 84 (fixing belt
module 86). For example, a nipping area N (nipping unit) in which
the heating belt 84 (fixing belt module 86) and the press roll 88
contact with each other is formed. In the nipping area N, a sheet K
as an example of the recording medium is pressed and heated, and a
toner image is fixed thereto.
[0211] The fixing belt module 86, for example, include the endless
heating belt 84, a heating press roll 89 on which the heating belt
84 is wound on the press roll 88 side and which rotatably driven
due to a rotational force of a motor (not shown) and presses the
heating belt 84 to the press roll 88 side from the inner surface
thereof, and a support roll 90 which supports the heating belt 84
from the inside in a position different from the heating press roll
89.
[0212] The fixing belt module 86, for example, include a support
roll 92 which is disposed outside of the heating belt 84 and
regulates a circuit path thereof, a posture correction roll 94
which corrects the posture of the heating belt 84 from the heating
press roll 89 to the support roll 90 and presses the heating belt
84 to the press roll 88 side from the inner surface thereof, and a
support roll 98 which applies tension to the heating belt 84 from
the inner surface thereof, at downstream of the nipping area N
which is an area in which the heating belt 84 (fixing belt module
86) and the press roll 88 contact with each other.
[0213] The fixing belt module 86 is provided so that a sheet-like
sliding member 82 is interposed between the heating belt 84 and the
heating press roll 89, for example.
[0214] The sliding member 82 is, for example, provided so that a
slide surface thereof contacts the inner surface of the heating
belt 84, and involved in holding and supplying a lubricant existing
between the sliding member and the heating belt 84.
[0215] Herein, the sliding member 82 is, for example, provided so
that both ends thereof are supported by supporting member 96.
[0216] The heating press roll 89 is a hard roll in which a fluorine
resin coating film having a basis weight of 200 .mu.m is formed on
a core surface as a protection layer which prevents metal abrasion
of the surface of a cylindrical core formed of aluminum.
[0217] A halogen heater 89A is, for example, provided inside of the
heating press roll 89, as an example of a heating source.
[0218] The support roll 90 is a cylindrical roll formed of
aluminum, includes a halogen heater 90A disposed at the inside
thereof as an example of a heating source, and heats the heating
belt 84 from the inner surface side.
[0219] Spring members (not shown) which press the heating belt 84
to the outer side are, for example, provided on both end portions
of the support roll 90.
[0220] The support roll 92 is, for example, a cylindrical roll
formed of aluminum and a release layer formed of a fluorine resin
with a thickness of 20 .mu.m is formed on the surface of the
support roll 92.
[0221] The release layer of the support roll 92 is, for example,
formed in order to prevent deposit of toner or paper powder from
the outer periphery surface of the heating belt 84 on the support
roll 92.
[0222] A halogen heater 92A is, for example, provided on the inner
portion of the support roll 92 as an example of a heating source,
and heats the heating belt 84 from the outer periphery surface
side.
[0223] That is, for example, the heating belt 84 is heated by the
heating press roll 89, the support roll 90, and the support roll
92.
[0224] The posture correction roll 94 is, for example, a columnar
roll formed of aluminum, and an end portion position measurement
mechanism (not shown) for measuring an end portion position of the
heating belt 84 is disposed in the vicinity of the posture
correction roll 94.
[0225] An axis displacement mechanism (not shown) for displacing
the contacting position of the heating belt 84 in an axial
direction depending on the measurement results of the end portion
position measurement mechanism is disposed on the posture
correction roll 94, and meandering of the heating belt 84 is
controlled.
[0226] Meanwhile, the press roll 88 has a configuration in which an
elastic layer 88B formed of silicone rubber and a peeling layer
including a fluorine resin having a film thickness of 100 .mu.m are
laminated in order from a base side, using a columnar roll 88A
formed of aluminum as a base. In addition, the press roll 88 is
rotatably supported, and is provided to be pressed at a portion
where the heating belt 84 is wound around the heating press roll
89, by a pushing unit such as spring (not shown). Accordingly, the
press roll is rotatably moved in an arrow F direction following the
heating belt 84 (heating press roll 89), in accordance with the
rotation movement of the heating belt 84 (heating press roll 89) of
the fixing belt module 86 in an arrow E direction.
[0227] The sheet K including an unfixed toner image is guided to
the nipping area N of the fixing device 80 and the image is fixed
by pressure and heat acting in the nipping area N.
[0228] The contact start position of the fixing device 80 of FIG. 3
is a position in the nipping area N, where the unfixed toner image
on the sheet K starts to contact the heating belt 84. In addition,
as shown in FIG. 3, the contact angle is an angle .theta. formed by
the contact surface (surface contacting the sheet K) of the heating
belt 84 in the contact start position in the direction opposite the
proceeding direction of the sheet K.
[0229] Hereinabove, the fixing device including the fixing belt
module including the heating belt and the press roll has been
described as an example of the fixing device in which the contact
angle is in the range described above, but there is no limitation
thereto, and a fixing device using a press belt instead of the
press roll may be used, or a fixing device using a fixing roll as
the fixing member contacting the toner image may be used.
[0230] In addition, the image forming apparatus of the exemplary
embodiment is not limited to an apparatus using the fixing device
in which the contact angle is in the range described above, and
other well-known image forming apparatus may be used.
[0231] Hereinafter, an example of the image forming apparatus
according to the exemplary embodiment will be described, but there
is no limitation thereto. Major parts shown in the drawings will be
described, but descriptions of other parts will be omitted.
[0232] FIG. 4 is a schematic configuration diagram showing an
example of the image forming apparatus according to the exemplary
embodiment including a developing device using the electrostatic
charge image developer according to the exemplary embodiment.
[0233] In the drawing, the image forming apparatus according to the
exemplary embodiment includes a photoreceptor 20 as an image
holding member which rotates in a predetermined direction, and
around this photoreceptor 20, a charging device 21 (an example of
the charging unit) which charges the photoreceptor 20 (an example
of the image holding member), an exposure device 22 (an example of
the electrostatic charge image forming unit), for example, as an
electrostatic charge image forming device which forms an
electrostatic charge image Z on the photoreceptor 20, a developing
device 30 (an example of the developing unit) which visualizes the
electrostatic charge image Z formed on the photoreceptor 20, a
transfer device 24 (an example of the transfer unit) which
transfers a toner image which is visualized on the photoreceptor 20
to a recording sheet 28 which is a recording medium, and a cleaning
device 25 (an example of the cleaning unit) which cleans toner
remaining on the photoreceptor 20 are disposed in order.
[0234] In the exemplary embodiment, as shown in FIG. 4, the
developing device 30 has a developing container 31 that contains a
developer G including a toner 40. This developing container 31 has
a developing opening 32 formed to be opposed to the photoreceptor
20, and a developing roll (developing electrode) 33 as a toner
holding member arranged to face the developing opening 32. When a
predetermined developing bias is applied to the developing roll 33,
a developing electric field is formed in a region (developing
region) sandwiched between the photoreceptor 20 and the developing
roll 33. In the developing container 31, a charge injection roll
(injection electrode) 34 as a charge injection member is provided
to be opposed to the developing roll 33. Particularly, in the
exemplary embodiment, the charge injection roll 34 also acts as a
toner supply roll for supplying the toner 40 to the developing roll
33.
[0235] Herein, the charge injection roll 34 may be rotated in an
arbitrarily selected direction, but in consideration of supply
properties of the toner and charge injection properties, it is
preferable that the charge injection roll 34 be rotated in the same
direction as that of the developing roll 33 at a part opposed to
the developing roll 33 with a difference in the peripheral velocity
(for example, 1.5 times or greater), and the toner 40 be interposed
in a region sandwiched between the charge injection roll 34 and the
developing roll 33 and rubbed to inject charges.
[0236] Next, an operation of the image forming apparatus according
to the exemplary embodiment will be described.
[0237] When an image forming process is started, first, the surface
of the photoreceptor 20 is charged by the charging device 21, the
exposure device 22 writes an electrostatic charge image Z on the
charged photoreceptor 20, and the developing device 30 visualizes
the electrostatic charge image Z as a toner image. Then, the toner
image on the photoreceptor 20 is transported to a transfer site,
and the transfer device electrostatically transfers the toner image
on the photoreceptor 20 onto a recording sheet 28 as a recording
medium. The toner remaining on the photoreceptor 20 is cleaned by
the cleaning device 25. Thereafter, the toner image on the
recording sheet 28 is fixed by a fixing device 36 (an example of
the fixing unit) to obtain an image.
[0238] Process Cartridge/Toner Cartridge
[0239] A process cartridge according to the exemplary embodiment
will be described.
[0240] The process cartridge according to the exemplary embodiment
is a process cartridge which includes a developing unit which
accommodates the electrostatic charge image developer according to
the exemplary embodiment and develops an electrostatic charge image
formed on a surface of an image holding member as a toner image by
the electrostatic charge image developer, and is detachable from
the image forming apparatus.
[0241] Without being limited to the configuration described above,
the process cartridge according to the exemplary embodiment may
have a configuration including a developing device and, if
necessary, at least one selected from other units such as the image
holding member, the charging unit, an electrostatic charge image
forming unit, and a transfer unit.
[0242] Hereinafter, an example of the process cartridge according
to the exemplary embodiment will be shown. However, there is no
limitation thereto. Major parts shown in the drawings will be
described, but descriptions of other parts will be omitted.
[0243] FIG. 5 is a schematic configuration diagram showing the
process cartridge according to the exemplary embodiment.
[0244] A process cartridge 200 shown in FIG. 5 is, for example,
configured by integrally combining and holding a photoreceptor 107
(an example of image holding member), a charging roll 108 (an
example of charging unit), a developing device 111 (an example of
developing unit), and a photoreceptor cleaning device 113 (an
example of cleaning unit) which are provided around the
photoreceptor 107, by attachment rails 116 and a housing 117 with
an opening portion 118 for exposure, and is configured as a
cartridge.
[0245] In FIG. 5, reference numeral 109 denotes an exposure device
(an example of electrostatic charge image forming unit), reference
numeral 112 denotes a transfer device (an example of transfer
unit), reference numeral 115 denotes a fixing device (an example of
fixing unit), and reference numeral 300 denotes a recording sheet
(an example of recording medium).
[0246] Next, a toner cartridge according to the exemplary
embodiment will be described. The toner cartridge according to the
exemplary embodiment may be configured so as to accommodate the
brilliant toner according to the exemplary embodiment and to be
detachable from the image forming apparatus. At least the toner may
be accommodated in the toner cartridge according to the exemplary
embodiment, and a developer, for example, may be accommodated
therein, depending on a mechanism of the image forming
apparatus.
[0247] The image forming apparatus shown in FIG. 4 has a
configuration in which a toner cartridge (not shown) is detachably
mounted thereon, and the developing device 30 is connected to the
toner cartridge via a toner supply tube (not shown). In addition,
when the toner accommodated in the toner cartridge runs low, the
toner cartridge may be replaced.
Examples
[0248] Hereinafter, the exemplary embodiment will be described in
more detail using examples, but is not limited to the following
examples. Unless otherwise noted, "parts" and "%" are based on
weight.
[0249] Preparation of Toner
[0250] Preparation of Toner Particles (1)
[0251] Synthesis of Binder Resin [0252] Bisphenol A ethylene oxide
2-mol adduct: 216 parts [0253] Ethylene glycol: 38 parts [0254]
Terephthalic acid: 200 parts [0255] Tetrabutoxytitanate (catalyst):
0.037 part
[0256] The above components are put in a two-necked flask which is
dried by heating, nitrogen gas is introduced in a container to
maintain an inert atmosphere, and the components are heated while
stirring, and then are subjected to co-condensation polymerization
reaction for 7 hours at 160.degree. C., and then a temperature
thereof is increased to 220.degree. C. while slowly reducing
pressure thereof to 10 Torr and those are maintained for 8 hours.
The pressure is temporarily returned to normal pressure, 9 parts of
trimellitic anhydride is added, and the pressure thereof is slowly
reduced again to 10 Torr and maintained for 2 hours at 220.degree.
C., to synthesize the binder resin.
[0257] Preparation of Resin Particle Dispersion [0258] Binder
resin: 160 parts [0259] Ethyl acetate: 233 parts [0260] Sodium
hydroxide aqueous solution (0.3 N): 0.1 part
[0261] The above components are put in a 1000 ml separable flask,
heated at 70.degree. C., and stirred with Three-One Motor
(manufactured by Shinto Scientific Co., Ltd.) to prepare a resin
mixed liquid. The resin mixed liquid is further stirred, 373 parts
of the ion exchange water is slowly added therein to perform phase
inversion emulsification, and the solvent thereof is removed to
obtain a resin particle dispersion (solid content concentration:
30%).
[0262] Preparation of Release Agent Dispersion [0263] Carnauba wax
(RC-160 manufactured by Toa Kasei Co., Ltd.): 50 parts [0264]
Anionic surfactant (NEOGEN RK manufactured by Dai-Ichi Kogyo
Seiyaku Co., Ltd.): 1.0 part [0265] Ion exchange water: 200
parts
[0266] The above components are mixed with each other and heated to
95.degree. C., dispersed using a homogenizer (ULTRA-TURRAX T50
manufactured by IKA Ltd.), and then are subjected to dispersion
treatment with Manton-Gaulin high pressure homogenizer
(manufactured by Gaulin Co., Ltd.) for 360 minutes, and thereby
preparing a release agent dispersion (solid content concentration:
20%) in which the release agent particles having the volume average
particle diameter of 0.23 .mu.m are dispersed.
[0267] Preparation of Brilliant Pigment Particle Dispersion [0268]
Aluminum pigment (2173EA manufactured by SHOWA ALUMINUM POWDER
K.K): 100 parts [0269] Anionic surfactant (NEOGEN R manufactured by
Dai-Ichi Kogyo Seiyaku Co., Ltd.): 1.5 parts [0270] Ion exchange
water: 900 parts
[0271] After removing a solvent from the paste of the aluminum
pigment, the above components are mixed and dispersed for 1 hour
using an emulsifying disperser CAVITRON (CR1010 manufactured by
Pacific Machinery & Engineering Co., Ltd.), and a brilliant
pigment particle dispersion (solid content concentration: 10%) in
which the brilliant pigment particles (particles of metal pigments)
which are particles of the aluminum pigment are dispersed is
prepared.
[0272] The value of the ratio (C/D) of the particles of the
aluminum pigment which is the metal pigment is 0.01 and the volume
resistivity thereof is 1.times.10.sup.-3 .OMEGA.cm.
[0273] Preparation of Toner Particles [0274] Resin particle
dispersion: 450 parts [0275] Release agent dispersion: 50 parts
[0276] Brilliant pigment particle dispersion: 21.74 parts [0277]
Nonionic surfactant (IGEPAL CA897): 1.40 parts
[0278] The above raw materials are put in a 2 L cylindrical
stainless container, dispersed and mixed for 10 minutes while
applying a shear force at 4000 rpm using a homogenizer
(ULTRA-TURRAX T50 manufactured by IKA Ltd.). Then, 1.75 parts of
10% nitric acid aqueous solution of polyaluminum chloride is slowly
added dropwise as an aggregating agent, the resultant material is
dispersed and mixed for 15 minutes by setting a rotating speed of
the homogenizer to 5000 rpm, and is set as a raw material
dispersion.
[0279] After that, the raw material dispersion is put in a
polymerization tank including a stirring device using stirring
blades of two paddles for forming a laminar flow and a thermometer,
heating is started with a mantle heater by setting a stirring
rotation speed to 810 rpm, and growth of aggregated particles is
promoted at 54.degree. C. At that time, pH of the raw material
dispersion is controlled to be in a range of 2.2 to 3.5 with 0.3N
nitric acid and 1 N sodium hydroxide aqueous solution. The raw
material dispersion is maintained in the pH range described above
for 2 hours and the aggregated particles are formed. At that time,
the volume average particle size of the aggregated particles
measured using Multisizer II (aperture size: 50 .mu.m, manufactured
by Beckman Coulter K.K) is 10.4 .mu.m.
[0280] Next, 100 parts of the resin particle dispersion is further
added and the resin particles of the binder resin are attached to
the surface of the aggregated particles. In addition, the
temperature thereof is increased to 56.degree. C., the aggregated
particles are prepared while confirming the size and form of the
particle with an optical microscope and Multisizer II. Then, after
increasing pH to 8.0 for coalescing the aggregated particles, the
temperature thereof is increased to 67.5.degree. C. After
confirming that the aggregated particles are coalesced with the
optical microscope, pH thereof is decreased to 6.0 while
maintaining the temperature at 67.5.degree. C., the heating is
stopped after 1 hour, and cooling is performed at a temperature
falling rate of 1.0.degree. C./min. Then, after performing sieving
with mesh of 20 .mu.m and repeating water washing, the resultant
material is dried with a vacuum drying machine to obtain toner
particles (1).
[0281] Preparation of Toner Particles (2) Toner particles (2) are
prepared in the same manner as in the preparation of the toner
particles (1), except for changing the stirring rotation speed in
the step of promoting the growth of aggregated particles from 810
rpm to 600 rpm and changing the temperature in the step of
coalescing the aggregated particles from 67.5.degree. C. to
74.degree. C.
[0282] Preparation of Toner Particles (3)
[0283] Toner particles (3) are prepared in the same manner as in
the preparation of the toner particles (1), except for changing the
stirring rotation speed in the step of promoting the growth of
aggregated particles from 810 rpm to 520 rpm and changing the
temperature in the step of coalescing the aggregated particles from
67.5.degree. C. to 80.degree. C.
[0284] Regarding the obtained toner particles (1) to (3), the value
of the ratio (C/D) ("ratio (C/D)" in Table 1), a rate of the metal
pigment in which the angle between the long axis direction of the
toner particles in the cross section in the thickness direction and
the long axis direction of the metallic pigment is from -30.degree.
to +30.degree. ("orientation of pigment" in Table 1), and the
volume average particle size (.mu.m) are shown in Table 1.
[0285] Preparation of Ti-Containing Particles 1
[0286] Ti-containing particles 1 are prepared as follows.
[0287] In detail, ilmenite as mineral ore is dissolved in sulfuric
acid to separate iron, the obtained TiOSO.sub.4 is hydrolyzed and
washing with water is performed until pH of the filtrated liquid
becomes constant. 3N hydrochloric acid is added thereto, after
adjusting pH to 6.5 to 7, strong sulfuric acid is added thereto,
the concentration of hydrochloric acid is adjusted to 110 g/L and
the concentration of TiO.sub.2 is adjusted to 50 g/L, the resultant
material is stirred at 30.degree. C. for 2 hours and then left, to
prepare TiO (OH).sub.2 slurry. 38 parts by weight of
tert-butyltrimethoxysilane is mixed with respect to 100 parts (in
terms of TiO (OH).sub.2) of the obtained TiO (OH).sub.2, followed
by stirring at 80.degree. C. for 30 minutes, 7N sodium hydroxide
aqueous solution is added thereto to neutralize pH to 6.8, and
filtration and water washing are performed using a suction funnel.
Then, after drying the resultant material at 120.degree. C. for 10
hours, soft aggregates are separated into pieces with a pin mill,
and Ti-containing particles 1 are prepared.
[0288] Preparation of Containing Particles 2
[0289] 400 g of 48% sodium hydroxide aqueous solution is added over
1 hour while stirring with respect to titanium dioxide hydrate cake
(solid content of 50%, containing 100 g in terms of TiO.sub.2)
obtained with a sulfate method, followed by heating and stirring at
100.degree. C. for 3 hours. The slurry is suctioned and filtrated,
and subjected to water washing until pH of the filtrated liquid is
6.5 to 7.0. Aqueous slurry with TiO.sub.2 conversion concentration
of 100 g/L is prepared, and 30% hydrochloric acid is added to
adjust pH to 6.8. The slurry is heated to 45.degree. C., 35%
hydrochloric acid is added at this temperature, and the
concentration of hydrochloric acid in the slurry is adjusted to 35
g/L. After further heating at 100.degree. C. for 3 hours, ammonia
water is added to adjust pH to 6.8. This slurry is suctioned and
filtrated and subjected to water washing until pH of the filtrated
liquid is 6.5 to 7.0. After drying, the soft aggregates are
separated into pieces with a pin mill, and Ti-containing particles
2 are prepared.
[0290] Preparation of Containing Particles 3
[0291] The obtained Ti-containing particles 2 are heated and dried
at 300.degree. C. for 15 minutes (under the nitrogen atmosphere),
and Ti-containing particles 3 are prepared.
[0292] Preparation of Ti-Containing Particles 4
[0293] 400 g of 48% sodium hydroxide aqueous solution is added over
1 hour while stirring with respect to titanium dioxide hydrate cake
(solid content of 50%, containing 100 g in terms of TiO.sub.2)
obtained with a sulfate method, followed by heating and stirring at
100.degree. C. for 3 hours. The slurry is suctioned and filtrated,
and subjected to water washing until pH of the filtrated liquid is
6.5 to 7.0. Aqueous slurry with TiO.sub.2 conversion concentration
of 100 g/L is prepared, and 30% hydrochloric acid is added to
adjust pH to 1.3. A SrCl aqueous solution is added to the cake
obtained by suctioning and filtrating this slurry to adjust a molar
ratio of SrO/TiO.sub.2 to 1.3. This slurry is heated at 85.degree.
C. for 2 hours and 48% sodium hydroxide aqueous solution is added
thereto and heating and mixing are continued for 20 hours. Then,
suction and filtration are performed and water washing is repeated
until pH of the filtrated liquid becomes constant. The obtained
cake is heated and dried at 110.degree. C., and Ti-containing
particles 4 are obtained.
[0294] Preparation of Ti-Containing Particles 5 Ti-containing
particles 5 are obtained in the same manner as the Ti-containing
particles 4, except for heating and mixing at 90.degree. C. for 48
hours the slurry in which a molar ratio of SrO/TiO.sub.2 is
adjusted to 1.3.
[0295] Preparation of Ti-Containing Particles 6
[0296] Ti-containing particles 6 are obtained in the same manner as
the Ti-containing particles 1, except for adjusting the
concentration of TiO.sub.2 to 100 g/L.
[0297] Preparation of Ti-Containing Particles 7 Ti-containing
particles 7 are obtained in the same manner as the Ti-containing
particles 1, except for adjusting the concentration of TiO.sub.2 to
150 g/L.
[0298] Preparation of Other External Additive 1 (SiO.sub.2
Particles) As the other external additive 1, irregular shaped
SiO.sub.2 particles (product name: RX 50 manufactured by Nippon
Aerosil Co., Ltd.) are used.
[0299] The moisture content, the number average particle size, the
value of the "ratio of height/long axis" of the Ti-containing
particles, which are acquired with the methods described above, are
shown in Table 1
[0300] Preparation of Toner
[0301] 0.4 part of the external additive disclosed in Table 1 is
added and mixed to 100 parts of the toner particles disclosed in
Table 1 with the Henschel mixer and each toner used in Examples and
Comparative Examples is obtained.
[0302] The value of the ratio (C/D) disclosed in Table 1 is
measured with the toner particles 1, 2, and 3 (that is, measured
before adding the external additive).
[0303] Preparation of Carrier [0304] Ferrite particles (volume
average particle size: 35 .mu.m): 100 parts [0305] Toluene: 14
parts [0306] Perfluoroacrylate copolymer (critical surface tension:
24 dyn/cm): 1.6 parts [0307] Carbon black (product name: VXC-72
manufactured by Cabot Corporation, volume resistivity: 100
.OMEGA.cm or lower): 0.12 part [0308] Crosslinked melamine resin
particles (average particle size: 0.3 .mu.m, toluene-insoluble):
0.3 part
[0309] First, carbon black is diluted with toluene and added to the
perfluoroacrylate copolymer and dispersed with a sand mill. Then,
each component other than the ferrite particles is dispersed
therein with a stirrer for 10 minutes, and a coating layer forming
solution is prepared. Then, after putting the coating layer forming
solution and the ferrite particles in a vacuum deaeration type
kneader and stirring for 30 minutes at a temperature of 60.degree.
C., the pressure is reduced and toluene is distilled to form a
resin coating layer and obtain a carrier.
[0310] Preparation of Developer
[0311] 36 parts of the toner and 414 parts of the carrier are put
in 2 liter V-blender, stirred for 20 minutes, and then sieved with
mesh of 212 .mu.m to prepare a developer.
[0312] Evaluation Test
[0313] Evaluation A of Brilliance
[0314] A solid image is obtained with the following method.
[0315] A developer unit of a modified DocuCentre-III C7600
(manufactured by Fuji Xerox Co., Ltd.) is filled with a developer
that is a sample, and 5 cm.times.5 cm solid images having a toner
applied amount of 4.0 g/cm.sup.2 are continuously formed on 10,000
recording sheets (OK TopCoat plus Paper manufactured by Oji Paper
Co., Ltd.) at the fixing temperature of 190.degree. C. and the
fixing load of 4.0 kg/cm.sup.2, after performing seasoning for a
night in the environment of a high temperature and low humidity
(35.degree. C. 50 RH %).
[0316] The ratio (A/B) of tenth and ten thousandth solid images are
measured with the following method. The value of the ratio (A/B) of
the tenth solid image is an "initial ratio (A/B)" and the value of
the ratio (A/B) of the ten thousandth solid image is a "physical
load-applied ratio (A/B)". The results are shown in Table 1.
[0317] The fixing device mounted on the image forming apparatus
used herein includes a fixing member having the following
configuration and characteristics and the contact angle is
27.degree..
[0318] Configuration of Fixing Member [0319] Base: thermosetting
polyimide [0320] Surface layer: layer of a
tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA)
containing graphite (graphite powder: ACP manufactured by Nippon
Graphite Industries, Ltd.) as a conductive material to be 3% by
weight of the total components
[0321] Characteristics of Fixing Member [0322] Surface resistivity:
1.times.10.sup.14.OMEGA./.quadrature. [0323] Volume resistivity:
1.times.10.sup.13 .OMEGA.cm
[0324] Measurement of Ratio (A/B)
[0325] Incident light at an angle of incidence of -45.degree. to
the solid image is applied on an image part of the formed solid
image by using a spectral varied angle color-difference meter
GC5000L manufactured by Nippon Denshoku Industries Co., Ltd. as a
goniophotometer, and a reflectance A at a light-receiving angle of
+30.degree. and a reflectance B at a light-receiving angle of
-30.degree. are measured. Each of the reflectance A and the
reflectance B is measured for light having a wavelength of 400 nm
to 700 nm at intervals of 20 nm, and defined as an average value of
the reflectances at respective wavelengths. The ratio (A/B) is
calculated from these measurement results.
[0326] Evaluation B of Brilliance
[0327] The evaluation B of brilliance is performed in the same
manner as in the evaluation A of brilliance, except for using an
image forming apparatus including the fixing member having the
following configuration and characteristics and on which the fixing
device having the contact angle of 27.degree. is mounted.
[0328] Configuration of Fixing Member [0329] Base: thermosetting
polyimide [0330] Surface layer: layer of a
tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA)
containing graphite (graphite powder: ACP manufactured by Nippon
Graphite Industries, Ltd.) as a conductive material to be 10% by
weight of the total components
[0331] Characteristics of Fixing Member [0332] Surface resistivity:
1.times.10.sup.9.OMEGA./.quadrature. [0333] Volume resistivity:
1.times.10.sup.8 .OMEGA.cm
[0334] Evaluation C of Brilliance
[0335] The evaluation C of brilliance is performed in the same
manner as in the evaluation A of brilliance, except for using an
image forming apparatus including the fixing member having the
following configuration and characteristics and on which the fixing
device having the contact angle of 15.degree. is mounted.
[0336] Configuration of Fixing Member [0337] Base: thermosetting
polyimide [0338] Surface layer: layer of a
tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA)
containing graphite (graphite powder: ACP manufactured by Nippon
Graphite Industries, Ltd.) as a conductive material to be 10% by
weight of the total components
[0339] Characteristics of Fixing Member [0340] Surface resistivity:
1.times.10.sup.9.OMEGA./.quadrature. [0341] Volume resistivity:
1.times.10.sup.8 .OMEGA.cm
TABLE-US-00001 [0341] TABLE 1 Evaluation of brilliance: ratio (A/B)
Toner particles Ti-containing particles Evaluation A Evaluation B
Evaluation C Volume Number After After After average Moisture
average Ratio of physical physical physical Ratio Orientation
particle content particle height/ Initial load is Initial load is
Initial load is (C/D) of pigment No. size (.mu.m) (% by weight)
size (nm) long axis No. stage applied stage applied stage applied
Ex. 1 0.075 85 1 12.5 5.5 30 0.5 1 65 63 68 63 70 68 2 0.208 70 2
13.0 5.5 30 0.5 1 25 20 3 0.45 62 3 12.2 5.5 30 0.5 1 6 3 4 0.075
85 1 12.5 2.5 20 0.4 2 67 38 5 0.075 85 1 12.5 1.0 20 0.4 3 68 18 6
0.075 85 1 12.5 6.0 40 0.7 4 61 35 7 0.075 85 1 12.5 5.5 55 0.7 5
65 15 8 0.075 85 1 12.5 5.3 35 0.4 6 63 18 68 50 70 58 9 0.075 85 1
12.5 5.6 25 0.8 7 66 13 70 30 68 50 Com. 1 0.075 85 1 12.5 -- -- --
-- 67 1 Ex. In Table, "--" indicates that the Ti-containing
particles are not contained, and the empty space indicates that the
evaluation is not performed.
[0342] From the results described above, it is found that, in the
examples, an image having a high brilliance is obtained even after
the physical load is applied, compared to the comparative
examples.
[0343] In addition, from the results described above, when an image
is formed under the conditions of the evaluation B of brilliance,
it is found that an image having a high brilliance is obtained even
after the physical load is applied, compared to a case where an
image is formed under the conditions of the evaluation A of
brilliance.
[0344] The foregoing description of the exemplary embodiments of
the present invention has been provided for the purposes of
illustration and description. It is not intended to be exhaustive
or to limit the invention to the precise forms disclosed.
Obviously, many modifications and variations will be apparent to
practitioners skilled in the art. The embodiments were chosen and
described in order to best explain the principles of the invention
and its practical applications, thereby enabling others skilled in
the art to understand the invention for various embodiments and
with the various modifications as are suited to the particular use
contemplated. It is intended that the scope of the invention be
defined by the following claims and their equivalents.
* * * * *